Anatomic and Surgical Aspects of Total Pancreatectomy in Swine.

BACKGROUND: The swine is a valuable model for preclinical research and surgical technique training. Induction of Type I diabetes is achieved by total pancreatectomy, therefore these animals may be used in several research studies, including islet transplantation field. Given the lack of information in the literature, the purpose of this work is to describe anatomic aspects of swine pancreas, the total pancreatectomy surgical technique, intra- and postoperative complications and the autopsy results. MATERIAL AND METHODS: Five hybrid male pigs, 20-35 kg, submitted to total pancreatectomy with duodenum, bile duct, and spleen preservation. Postoperatively, daily clinical assessment and capillary blood glucose collection were performed. At the end of the 30-day period or in the occurrence of serious clinical complications, euthanasia and autopsy were performed. RESULTS: The average duration of surgery was 128 minutes, without intraoperative deaths or anesthesia induction failures. The median survival was 6.6 days. Postoperative complications were weight loss (3), emesis (2), constipation (2), abdominal distension (2), diarrhea (1), and loss of appetite (1). All animals were euthanized due to serious complications. Two animals presented surgical complications (duodenal necrosis with gastroparesis and internal hernia with intestinal necrosis). The other 3 animals presented serious clinical complications related to exocrine pancreatic insufficiency due to deficiency of pancreatic enzymes. Glycemic values above 200 mg/dL were found on the first postoperative day and above 300 mg/dL on the seventh day in all animals. CONCLUSION: A model of total pancreatectomy with duodenum, spleen, and bile duct preservation in pigs was established. All animals became diabetic, however, animals without postoperative complications were euthanized due to serious complications related to pancreas exocrine insufficiency.

Islet transplantation: overcoming the organ shortage.

BACKGROUND: Type 1 diabetes mellitus (T1D) is a condition resulting from autoimmune destruction of pancreatic ß cells, leading patients to require lifelong insulin therapy, which, most often, does not avoid the most common complications of this disease. Transplantation of isolated pancreatic islets from heart-beating organ donors is a promising alternative treatment for T1D, however, this approach is severely limited by the shortage of pancreata maintained under adequate conditions. METHODS: In order to analyze whether and how this problem could be overcome, we undertook a retrospective study from January 2007 to January 2010, evaluating the profile of brain-dead human pancreas donors offered to our Cell and Molecular Therapy NUCEL Center ( www.usp.br/nucel ) and the basis for organ refusal. RESULTS: During this time period, 558 pancreata were offered by the São Paulo State Transplantation Central, 512 of which were refused and 46 were accepted for islet isolation and transplantation. Due to the elevated number of refused organs, we decided to analyze the main reasons for refusal in order to evaluate the possibility of improving the organ acceptance rate. The data indicate that hyperglycemia, technical issues, age, positive serology and hyperamylasemia are the top five main causes for declination of a pancreas offer. CONCLUSIONS: This study underlines the main reasons to decline a pancreas offer in Sao Paulo-Brazil and provides some guidance to ameliorate the rate of eligible pancreas donors, aiming at improving the islet isolation and transplantation outcome. TRIAL REGISTRATION: Protocol CAPPesq number 0742/02/CONEP 9230.

Traditional and Advanced Cell Cultures in Hematopoietic Stem Cell Studies.

Hematopoiesis is the main function of bone marrow. Human hematopoietic stem and progenitor cells reside in the bone marrow microenvironment, making it a hotspot for the development of hematopoietic diseases. Numerous alterations that correspond to disease progression have been identified in the bone marrow stem cell niche. Complex interactions between the bone marrow microenvironment and hematopoietic stem cells determine the balance between the proliferation, differentiation and homeostasis of the stem cell compartment. Changes in this tightly regulated network can provoke malignant transformation. However, our understanding of human hematopoiesis and the associated niche biology remains limited due to accessibility to human material and the limits of in vitro culture models. Traditional culture systems for human hematopoietic studies lack microenvironment niches, spatial marrow gradients, and dense cellularity, rendering them incapable of effectively translating marrow physiology ex vivo. This review will discuss the importance of 2D and 3D culture as a physiologically relevant system for understanding normal and abnormal hematopoiesis.

Immobilization of primary cultures of insulin-releasing human pancreatic cells.

Transplantation of pancreatic islets isolated from organ donors constitutes a promising alternative treatment for type1 Diabetes, however, it is severely limited by the shortage of organ donors. Ex-vivo islet cell cultures appear as an attractive but still elusive approach for curing type 1 Diabetes. It has recently been shown that, even in the absence of fibrotic overgrowth, several factors, such as insufficient nutrition of the islet core, represent a major barrier for long-term survival of islets grafts. The use of immobilized dispersed cells may contribute to solve this problem due to conceivably easier nutritional and oxygen support to the cells.  Therefore, we set out to establish an immobilization method for primary cultures of human pancreatic cells by adsorption onto microcarriers (MCs). Dispersed human islets cells were seeded onto Cytodex1 microcarriers and cultured in bioreactors for up to eight days. The cell number increased and islet cells maintained their insulin secretion levels throughout the time period studied. Moreover, the cells also presented a tendency to cluster upon five days culturing.  Therefore, this procedure represents a useful tool for controlled studies on islet cells physiology and, also, for biotechnological applications.